Bungee jumping : the math(s)

May 29th, 2015

bungee-mathsIf the physics and mathematics of bungee jumping are amongst your interests, you are, as they say, spoilt for choice. There are quite a number of readily accessible academic studies at your disposal. Might we suggest (in no particular order)…

• Understanding the physics of bungee jumping by A. Heck, P. Uylings, E. Kędzierska

• Bungee jump model with increased stretch-prediction accuracy
by J. W. Kockelman, M. Hubbard

• The Greater-Than-g Acceleration of a Bungee Jumper
by David Kagan and Alan Kott

The Mechanics of Bungee Jumping
by D. R. H. Jones
Safety notes: Before embarking on any practical bungee-based experiments involving humans, it might be an idea to read this advice provided by the University of Maryland, US.

DANGER – IMPORTANT NOTE: Bungee cords are made of shock cords (elastomers) or from rubber. They DO NOT behave as linear springs. It would be dangerous to assume linearity of a real bungee jumping cord and make calculations on this basis.

Also see: Give ‘Em Enough Rope: Perception of Health and Safety Risks in Bungee Jumpers



Eric Aston joins Luxuriant Flowing Hair Club for Scientists (LFHCfS)

May 28th, 2015

D. Eric Aston has joined the Luxuriant Facial Hair Club for Scientists (LFHCfS). He says:

I am a colloid scientist, chemical engineer, and professor who pretends to be a physicist when I play with lasers for Raman spectroscopy in my microscopy lab. I teach thermodynamics and other stuff—more recently creative writing—and once donated my abundant locks for someone else to sport. I believe my hair has given me stories in a Jungian sense; if you know what that means, please inform me.

D. Eric Aston, Ph.D, LFHCfS
Professor & Interim Department Chair
Chemical & Materials Engineering
University of Idaho
Moscow, Idaho, USA



Shepherd physics: Capturing a skittish lamb, using statistical physics

May 28th, 2015

A trio of theoretical physicists have recently used ideas from statistical mechanics and probability theory to try to develop an optimal strategy for capturing a skittish lamb near a precipice.

The situation that they model is an idealization of “the capture of a diffusing, but skittish lamb, with an approaching shepherd on the left and a precipice on the right.” They approached this problem by examining first-passage probabilities, which describe the first time of some event (e.g., a lamb falling off of a cliff) occurring. The physicists summarized their strategy as follows:

In particular, the probability to capture the lamb is maximized when the shepherd moves at a non-zero optimal speed if the initial lamb position and the ratio between the two boundary speeds satisfy certain conditions.

Here’s further detail from the study:


One of the physicists, Sid Redner, works at the Santa Fe Institute, so perhaps the next problem he’ll attempt is to design a strategy to help Wile E. Coyote catch the Roadrunner.

BONUS: Redner on the question: In a pro basketball game, when is a lead safe?

Podcast #13: Telephones for animals

May 27th, 2015

The California inventor (and Taser Corporation advisor) of a telephone for animals and a cell phone that reaches out and shocks bad guys, borborygmi (the sounds made by your intestines), the phrase “I don’t know”, and other things turn up  in this week’s Improbable Research podcast.

SUBSCRIBE on Play.it or iTunes, to get a new episode every week, free.
[NEWS: Soon, the podcast will also be available on Spotify.]

This week, Marc Abrahams tells about:



The mysterious John Schedler perhaps did the sound engineering this week.

The Improbable Research podcast is all about research that makes people LAUGH, then THINK — real research, about anything and everything, from everywhere —research that may be good or bad, important or trivial, valuable or worthless. CBS distributes it, both on the new CBS Play.it web site, and on iTunes (and soon, also on Spotify).

People-calculating: open doors and closed doors

May 26th, 2015

RosenbaumWhether one person holds a door open for another is not simply a question of etiquette, says a study by Joseph P Santamaria and David A Rosenbaum [pictured here] of Pennsylvania State University. No, they say. Nothing simple about it.

Santamaria and Rosenbaum worked to pursue the answer through a tangle of belief, logic, probability, perception and calculation. Their study, Etiquette and Effort: Holding Doors for Others, was published in 2011 in the journal Psychological Science. It is, one way or another, a gripping read....

—So begins the latest Improbable Research column in The Guardian.

BONUS: This graph is from an economist’s alternative take on the question:

door open